Minimally invasive surgical techniques have revolutionized cardiac surgery. Minimally invasive cardiac surgery enjoys the advantages of reduced morbidity, quicker recovery times, and improved cosmesis over conventional open-chest cardiac surgery in which the surgeon "cracks" open a patient's chest by sawing through the breastbone or sternum. Recent advances in endoscopic instruments and percutaneous access to a patient's thoracic cavity have made minimally invasive surgery possible. Reduction in morbidity, lower cost, and reduced trauma has made minimally invasive surgery desirable.
One approach to minimally invasive cardiac surgery is an endoscopic procedure in which access to the heart is gained through several small openings, or ports, in the chest wall of a patient. The endoscopic method allows surgeons to stop the heart without cracking the chest by utilizing a series of internal catheters to stop blood flow through the aorta and to administer cardioplegia solution to facilitate stopping the heart. The endoscopic approach utilizes groin cannulation to establish cardiopulmonary bypass (CPB) which takes over the function of the heart and lungs by circulating oxygenated blood throughout the body. After CPB is started, an intraaortic balloon catheter that functions as an internal aortic clamp by means of an expandable balloon at its distal end is used to occlude blood flow in the ascending aorta from within. A full description of an example of one preferred endoscopic technique is found in U.S. Pat. No. 5,452,733, the complete disclosure of which is incorporated by reference herein. A primary drawback of endoscopic cardiac surgery procedures, however, is that such procedures do not avoid the damaging effects of CPB. CPB has been shown to be the cause of many of the complications that have been reported in conventional coronary artery bypass graft (CABG) procedures, such as stroke. The period of cardiopulmonary bypass should be minimized, if not avoided altogether, to reduce patient morbidity.
An approach to minimally invasive cardiac surgery that avoids CPB is minimally invasive direct coronary artery bypass grafting (MIDCAB) on a beating heart. Using this method, the heart typically is accessed through a mini-thoracotomy (i.e., a 6 to 8 cm incision in the patient's chest) which also avoids the sternal splitting incision of conventional cardiac surgery. The anastomosis procedure is then performed under direct vision on the beating heart. However, there are many obstacles to precise coronary anastomosis during MIDCAB. In particular, the constant translational motion of the heart and bleeding from the opening in the coronary artery hinder precise suture placement in the often tiny coronary vessel.
In response to problems associated with the above-described minimally invasive surgical techniques, a new surgical platform known as the TRANSARREST.TM. platform has been developed to minimize the cardiac motion of the beating heart. The TRANSARREST.TM. platform employs a novel pharmaceutical approach to stabilizing the heart. This revolutionary pharmaceutical approach to cardiac stabilization is fully described in co-pending provisional patent application for Compositions, Apparatus and Methods For Facilitating Surgical Procedures, Ser. No. 60/055,127, filed Aug. 8, 1997 and invented by Francis G. Duhaylongsod, M.D, the entire contents of which are expressly incorporated by reference herein. As described therein, pharmaceutical compositions, devices, and methods are provided which are useful for medical and surgical procedures which require precise control of cardiac contraction, such as minimally invasive CABG procedures. Generally, the TRANSARREST.TM. platform involves the intracoronary administration of a novel drug composition which provides for precise heart rate and rhythm control management while maintaining the ability of the heart to be electrically paced. Electrical pacing wires are connected to the right ventricle and/or left ventricle and/or atria and are used to pace the heart using a novel foot-actuated pacer control system to maintain the patient's blood circulation during the periods in which the surgeon is temporarily not performing the surgical procedure. Thus, for example, in a CABG procedure, the surgeon can control the pacing of the heart with a convenient foot pedal and can controllably stop the heart as sutures are placed in the vessel walls. The pharmaceutical compositions, devices and methods for drug delivery, and systems for pacing the heart, give a surgeon complete control of the beating heart.
The TRANSARREST.TM. procedure described above can be used to facilitate any surgical procedure within the thoracic cavity or other body cavity which requires intermittent stoppage of the heart or elimination of movements caused by pulsatile blood flow, whether access is gained to the body cavity via a partial or median stemotomy incision, via a mini-thoracotomy incision, or via one or more small incisions or ports in the chest wall. Ideally, the least invasive manner in which to perform the surgical procedure is through small incisions and/or trocar sleeves disposed in the chest wall, which avoids the morbidity and reduces the pain and trauma associated with open surgical procedures. However, in order to perform the TRANSARREST.TM. surgical procedure, or any other thoracoscopic procedure least invasively, new highly specialized microsurgical instruments and methodologies are required since the minimally invasive cardiac surgery field is relatively new and evolving. In particular, a microsurgical cutting instrument is needed which preferably can be inserted into a body cavity percutaneously via a small port incision, accurately manipulated from outside the body cavity, and adapted to be used for extremely small scale microsurgical cutting procedures within the body cavity. Preferably, the surgical cutting tool should be adapted to perform the fine incisions required for an arteriotomy, aortotomy, atriotomy or other similar incision in the tiny coronary vessels, other great vessels of the heart, or peripheral vessels, to facilitate coronary anastomosis, for example. The instrument preferably should be used in concert with remote viewing devices, such as an endoscope, thoracoscope, and the like that can be inserted through small incisions and used to view the operative site.
Over the past decade, cutting instruments have been developed to facilitate minimally invasive surgical techniques, particularly in the areas of arthroscopy, laproscopy, pelviscopy, and the like. Such procedures typically target large internal body structures and involve both the excision and removal of large masses of body tissue during the surgery. The cutters used for such procedures typically employ some form of rotary or linearly reciprocating device to cut the tissue and vacuum means to remove the tissue from the body cavity, such as in arthroscopic joint procedures. An example of a rotary device used for tissue excision and removal is U.S. Pat. No. 4,203,444 to Bonnell et al. The Bonnell device utilizes an outer tube having a side-facing, axially extending cutting port and an internal rotary blade. A vacuum conduit draws the tissue to be sheared into the cutting port while the rotary blade is driven in shearing relation to the external tube. The vacuum further draws the cut body tissue through a tube lateral to the handle and out of a side port of the instrument for disposal. An example of a linearly reciprocating tissue cutter for excising and removing body tissue during surgery is found in U.S. Pat. No. 5,527,332 to Clement. These cutting instruments, and other similar morcellator-type instruments used for minimally invasive arthroscopic and laproscopic procedures, lack the high degree of precision and control necessary for microsurgical cutting procedures on very small body structures, such as the tiny coronary vessels, and particularly are not well suited for cutting procedures in which it is damaging to remove any substantial portion of the body structure.
Instruments have been developed to facilitate thoracoscopic CABG and other minimally-invasive microsurgical cutting procedures on small body structures within the thoracic cavity, such as the microsurgical devices described in U.S. Pat. No. 5,501,698. The endoscopic surgical cutting instruments described therein have an end-effector for cutting tissue in the form of forward or rearward-cutting scissors disposed at the distal end of an extended shaft. The scissors are manipulated from the proximal end of the shaft outside the body cavity to make small incisions in a target coronary artery or other vessel or small body structure, which is typically several inches away from the actuating mechanism at the proximal end of the device. The drawback of such cutting devices is that it is difficult to precisely control the cutting motion of the distal end-effector. Because the vessel is several inches away from the proximal end of the device, any slight movement at the proximal end of the tool will cause the distal, cutting end of the tool to jump or bounce, i.e., move in an exaggerated manner. Such surgical cutting tools provide no mechanism to stabilize the distal, cutting end of the tool to precisely control the location, depth, and length of the cut in the target vessel or other small body structure.
A need therefore exists for a surgical cutting instrument and method to facilitate the performance of minimally-invasive microsurgical procedures, and particularly, the performance of thoracoscopic CABG and other procedures on the heart and coronary and/or peripheral vessels. The surgical cutting instrument preferably should be adapted to be percutaneously inserted into a body cavity, such as the thoracic cavity, through small incisions or trocar sleeves in the chest wall, and simply, quickly, and precisely manipulated from outside the body cavity to make very fine incisions in the coronary vessels (or other small body structure) without substantially removing any portion of the vessels. The surgical cutting instrument must have a length sufficient to reach the heart and other thoracic organs and vessels from various percutaneous access points. Preferably, the surgical cutting instrument should have the capability to stabilize the distal end of the instrument to minimize any unwanted movements of the device during the actual cutting operation.